1. Field of the Invention
The present invention relates to a liquid droplet transporting apparatus which transports a liquid droplet by using an electrowetting phenomenon, a valve, a memory, and a display unit.
2. Description of the Related Art
A technology of transporting a liquid droplet by using a phenomenon in which a liquid repellent property (wetting angle) on a surface of an insulating layer when an electric potential difference is generated on both sides of the insulating layer is changed (electrowetting phenomenon) has hitherto been known. For example, a micro liquid droplet (very small size liquid droplet) transporting device described in Japanese Patent Application Laid-open No. 2005-257569 includes two electrodes (a first electrode and a second electrode) provided to be isolated on a surface of a substrate, a dielectric film which covers the first electrode, and a hydrophobic (water repellent) film (insulating layer) which covers surfaces of the dielectric film and the second electrode continuously. In this liquid droplet transporting device, when a voltage is applied between the two electrodes with a liquid droplet positioned between the two electrodes while making a contact with both areas at which the two electrodes are arranged, a wetting angle of a surface of the hydrophobic film in the area at which the first electrode is arranged and the dielectric film is formed becomes smaller than a wetting angle of a surface of the hydrophobic film in the area at which the second electrode is arranged and the dielectric film is not formed. Therefore, a difference in the wetting angle becomes a driving force, and the liquid droplet is transported from the second electrode to the first electrode in one direction.
The micro liquid droplet transporting device described in Japanese Patent Application Laid-open No. 2005-257569 moves the liquid droplet from one electrode to the other electrode in one direction. On the other hand, apart from such apparatus, also an apparatus which transports a very micro liquid droplet between two areas in which electrodes are arranged has been desired in various fields. In this case, when it is possible to detect as to which area among the two areas the liquid droplet exists, such an apparatus would be highly applicable markedly.